Improving the Mechanical Behavior of Anthracene-Contaminated Kaolinite Clay Using Portland Cement and Lime

Leakage of hydrocarbon organic fluids into the soil usually causes a reduction in its bearing capacity and performance. Cementation is one of the most effective and suitable solutions to improve the geotechnical parameters of contaminated clays. In this study, the effect of Portland cement (3, 6 and 9%) and lime (10, 20 and 30%) on improvement of kaolinite clay contaminated with anthracene (0.06, 0.09 and 0.12%) was investigated by performing an experimental study. For this purpose, the samples were prepared as mixtures of clean or anthracene-contaminated clay with different cement and lime contents for a curing time of 7 days. Then, unconfined compressive strength (UCS) tests were conducted on the samples. The results showed the strength reduction of anthracene-contaminated kaolinite clay compared to the clean soil. The reduction in the unconfined strength was about 46% with an increase in degree of contamination up to 0.12%. Adding Portland cement and lime to the clean and contaminated soil increased the compressive strength. As, the addition of 3% Portland cement or 10% lime to clay contaminated with 0.12% anthracene increased UCS up to 4 times. Thus, according to the results of soil improvement, the strength of soil-cement mixture containing 3% Portland cement is approximately equal to that of soil-lime containing 10% lime. Both the Portland cement and lime were capable of improving the strength of anthracene-contaminated soil. However, the rate of improvement by cement was more than that of lime. The main reason was due to the reduction of double layer thickness which causes flocculation of particles and tendency of clay structure to behave like granular soils.